Shield machine for use in a shield tunneling method for constructing a small diameter tunnel

摘要

A small diameter shield tunnel is constructed by using a shield machine (10) and assembling within a tail portion (12) of the machine a set of three 120° arcuate segments into a segment ring. An annular seal device (23) is axially movably provided between the outer periphery of the segment ring (20) and the inner periphery of a tail skin plate (22) defining the tail portion of the machine. A back-­filling material is charged into an annular gap formed between the outer peripheral surface of the segment ring and natural soil surrounding the segment ring. The back-filling material within the annular gap is compressed by the seal device which (23) is caused to move between the inner peripheral surface of the tail skin plate and the outer peripheral surface of the segment ring, in the axial direction of the tunnel, away from a face where excavation of natural soil is carried out mechanically.